U.S. patent application number 11/419927 was filed with the patent office on 2007-11-29 for method for detecting presence of silver-containing antimicrobial agents.
This patent application is currently assigned to Eastman Kodak Company. Invention is credited to Sidney J. Bertucci.
Application Number | 20070275472 11/419927 |
Document ID | / |
Family ID | 38750012 |
Filed Date | 2007-11-29 |
United States Patent
Application |
20070275472 |
Kind Code |
A1 |
Bertucci; Sidney J. |
November 29, 2007 |
METHOD FOR DETECTING PRESENCE OF SILVER-CONTAINING ANTIMICROBIAL
AGENTS
Abstract
A method for testing for presence of silver metal or silver salt
antimicrobial agents on a surface of substrate, comprising a)
contacting the substrate with a dye solution, wherein the dye
solution comprises a dye selected to provide a detectable
differential color change in the dye solution contacted substrate
for a substrate having silver metal or silver salt on a surface
thereof relative to a substrate not having silver metal or silver
salt on a surface thereof, and b) detecting a presence or absence
of the differential color change in the dye solution contacted
substrate.
Inventors: |
Bertucci; Sidney J.;
(Rochester, NY) |
Correspondence
Address: |
Paul A. Leipold, Patent Legal Staff;Eastman Kodak Company
343 State Street
Rochester
NY
14650-2201
US
|
Assignee: |
Eastman Kodak Company
|
Family ID: |
38750012 |
Appl. No.: |
11/419927 |
Filed: |
May 23, 2006 |
Current U.S.
Class: |
436/80 |
Current CPC
Class: |
G03C 1/035 20130101;
G03C 2001/03517 20130101; G01N 21/78 20130101; G01N 31/22 20130101;
G03C 1/12 20130101 |
Class at
Publication: |
436/80 |
International
Class: |
G01N 33/20 20060101
G01N033/20 |
Claims
1. A method for testing for presence of silver metal or a silver
salt on a surface of substrate, comprising a) contacting the
substrate with a dye solution, wherein the dye solution comprises a
dye selected to provide a detectable differential color change in
the dye solution contacted substrate for a substrate having silver
metal or silver salt on a surface thereof relative to a substrate
not having silver metal or silver salt on a surface thereof, and b)
detecting a presence or absence of the differential color change in
the dye solution contacted substrate.
2. The method of claim 1, wherein the dye solution comprises a dye
selected to have a greater adsorption affinity for a silver salt
relative to that for the substrate or to have a detectable
different color when adsorbed to a silver salt relative to color
when adsorbed to the substrate, and wherein the dye solution tests
directly for the presence of a silver salt on a surface of the
substrate, or tests indirectly for the presence of silver metal by
converting a surface of the silver metal in situ to a silver
salt.
3. The method of claim 2, wherein the dye solution comprises a dye
having a greater adsorption affinity for silver halide relative to
that for the substrate or has a detectable different color when
adsorbed to silver halide relative to color when adsorbed to the
substrate, and wherein the dye solution further comprises soluble
halide salt and the method tests for the presence of metallic
silver by in situ conversion of the surface of the metallic silver
to silver halide in the presence of environmental oxygen or added
oxidizing agent dissolved in the dye solution.
4. The method of claim 1, wherein the differential color change is
human visually detectable.
5. The method of claim 1, wherein the dye is selected based on a
color of the substrate to provide a human visually detectable
differential color change.
6. The method of claim 1, wherein the method is performed on a test
substrate previously treated with a substrate processing solution
to verify presence or absence of silver metal or silver salt in the
substrate processing solution.
7. The method of claim 1, wherein the method tests for presence of
silver halide particles deposited on a surface of a substrate, and
the dye solution comprises a dye having a greater adsorption
affinity for silver halide relative to that for the substrate or
has a detectable different color when adsorbed to silver halide
relative to color when adsorbed to the substrate.
8. The method of claim 7, wherein the dye comprises a photographic
sensitization dye.
9. The method of claim 7, wherein the dye comprises a cyanine dye
including two basic heterocyclic nuclei joined by a methine
linkage.
10. The method of claim 9, wherein the dye comprises a quinolinium,
benzoxazolium, or benzothiazolium dye.
11. The method of claim 9, wherein the dye comprises a salt of
1-ethyl-2-((1-ethyl-2(1H)-quinolinylidene)methyl)-quinolinium.
12. The method of claim 7, wherein the silver halide particles are
predominantly silver chloride.
13. The method of claim 12, wherein the dye solution further
comprises soluble bromide or iodide ions in an amount effective to
enhance the detectable differential color change in the dye
solution contacted substrate obtained for a substrate having silver
chloride particles on a surface thereof relative to a substrate not
having silver chloride particles on a surface thereof.
14. A method of coating a substrate with a silver-containing
composition to provide antimicrobial properties comprising:
providing a composition comprising a silver-containing
antimicrobial agent; providing a substrate; coating the substrate
with said composition; and verifying presence of silver-containing
antimicrobial agent deposited on a surface of the substrate by
contacting the substrate with a dye solution, wherein the dye
solution comprises a dye selected to provide a detectable
differential color change in the dye solution contacted substrate
for a substrate having silver-containing antimicrobial agent on a
surface thereof relative to a substrate not having
silver-containing antimicrobial agent on a surface thereof, and
detecting a presence or absence of the differential color change in
the dye solution contacted substrate.
15. The method of claim 14, wherein the composition comprises
water, silver halide particles, and a binder; and wherein the dye
solution comprises a dye having a greater adsorption affinity for
silver halide relative to that for the substrate or has a
detectable different color when adsorbed to silver halide relative
to color when adsorbed to the substrate.
16. The method of claim 15, wherein the silver halide particles are
predominantly silver chloride, and wherein the dye solution further
comprises soluble bromide or iodide ions in an amount effective to
enhance the detectable differential color change in the dye
solution contacted substrate obtained for a substrate having silver
chloride particles on a surface thereof relative to a substrate not
having silver chloride particles on a surface thereof.
17. A method for testing for presence of silver-containing
antimicrobial agent in a treatment solution, comprising a)
contacting a sample of the treatment solution with a dye solution,
wherein the dye solution comprises a dye selected to provide a
detectable differential color change in the dye solution contacted
treatment solution for a treatment solution having
silver-containing antimicrobial agent therein relative to a
treatment solution not having silver-containing antimicrobial agent
therein, and b) detecting a presence or absence of the differential
color change in the dye solution contacted treatment solution.
18. The method of claim 17, further comprising treating a substrate
with the treatment solution to coat the substrate with the
silver-containing antimicrobial agent.
19. The method of claim 17, wherein the treatment solution
comprises water, silver halide particles, and a binder; and wherein
the dye solution comprises a dye having adsorption affinity for
silver halide and which provides a detectable different color when
adsorbed to silver halide relative to color when not adsorbed to
silver halide.
20. The method of claim 19, wherein the silver halide particles are
predominantly silver chloride, and wherein the dye solution further
comprises soluble bromide or iodide ions in an amount effective to
enhance the detectable differential color change in the dye
solution contacted treatment solution for a treatment solution
having silver chloride particles therein relative to a treatment
solution not having silver chloride particles therein.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a method for detecting
presence of silver-containing antimicrobial agents on a surface of
a substrate or in treatment solutions. More particularly, it
relates to testing for presence of antimicrobial silver metal and
silver salts that may be applied to a substrate such as a target
fiber or textile fabric.
BACKGROUND OF THE INVENTION
[0002] The antimicrobial properties of silver have been known for
several thousand years. The general pharmacological properties of
silver are summarized by Stewart C. Harvey in Chapter 41,
"Antiseptics and Disinfectants: Fungicides; Ectoparasiticides" (pp
964-987) of The Pharmacological Basis of Therapeutics, Fifth
Edition, by Louis S. Goodman and Alfred Gilman (editors), published
by MacMillan Publishing Company, NY, 1975 (see "Heavy Metals and
Their Salts", pp 975-977). It is now understood that the affinity
of silver ion for biologically important moieties such as
sulfhydryl, amino, imidazole, carboxyl and phosphate groups are
primarily responsible for its antimicrobial activity.
[0003] The attachment of silver ions to one of these reactive
groups on a protein results in the precipitation and denaturation
of the protein. The extent of the reaction is related to the
concentration of silver ions. The diffusion of silver ion into
mammalian tissues is self-regulated by its intrinsic preference for
binding to proteins through the various biologically important
moieties on the proteins, as well as precipitation by the chloride
ions in the environment. Thus, the very affinity of silver ion to a
large number of biologically important chemical moieties (an
affinity which is responsible for its action as a
germicidal/biocidal/viricidal/fungicidal/bacteriocidal agent) is
also responsible for limiting its systemic action--silver is not
easily absorbed by the body. This is a primary reason for the
tremendous interest in the use of silver containing species as an
antimicrobial i.e. an agent capable of destroying or inhibiting the
growth of microorganisms, including bacteria, yeast, fungi and
algae, as well as viruses.
[0004] In addition to the affinity of silver ions for biologically
relevant species, which leads to the denaturation and precipitation
of proteins, some silver compounds, those having low ionization or
dissolution ability, also function effectively as antiseptics.
Distilled water in contact with metallic silver bercomes
antibacterial even though the dissolved concentration of silver
ions is less than 100 ppb. There are numerous mechanistic pathways
by which this oligodynamic effect is manifested i.e. by which
silver ion interferes with the basic metabolic activities of
bacteria at the cellular level, thus leading to a bacteriocidal
and/or bacteriostatic effect.
[0005] A detailed review of the oligodynamic effect of silver can
be found in "Oligodynamic Metals" by I. B. Romans in Disinfection,
Sterlization and Preservation, C. A. Lawrence and S. S. Bloek
(editors), published by Lea and Fibiger (1968) and "The
Oligodynamic Effect of Silver" by A. Goetz, R. L. Tracy and F. S.
Harris, Jr. in Silver in Industry, Lawrence Addicks (editor),
published by Reinhold Publishing Corporation, 1940. These reviews
describe results that demonstrate that silver is effective as an
antimicrobial agent towards a wide range of bacteria.
[0006] One very important use of silver based antimicrobial agents
is for textiles. Various methods are known in the art to render
antimicrobial properties to a target fiber. The approach of
embedding inorganic antimicrobial agents, such as zeolites, into
low melting components of a conjugated fiber is described in U.S.
Pat. No. 4,525,410 and U.S. Pat. No. 5,064,599. In another
approach, the antimicrobial agent may be delivered during the
process of making a synthetic fiber such as those described in U.S.
Pat. No. 5,180,402, U.S. Pat. No. 5,880,044, and U.S. Pat. No.
5,888,526, or via a melt extrusion process as described in U.S.
Pat. No. 6,479,144 and U.S. Pat. No. 6,585,843. In still yet
another process an antimicrobial metal ion may be ion exchanged
with an ion exchange fiber as described in U.S. Pat. No.
5,496,860.
[0007] Methods of transferring an antimicrobial agent, in the form
of an inorganic metal salt or zeolite, from one substrate to a
fabric are disclosed in U.S. Pat. No. 6,461,386. High-pressure
laminates containing antimocrobial inorganic metal compounds are
disclosed in U.S. Pat. No. 6,248,342. Deposition of antimicrobial
metals or metal-containing compounds onto a resin film or target
fiber has also been described in U.S. Pat. No. 6,274,519 and U.S.
Pat. No. 6,436,420.
[0008] It is also known in the art that fibers may be rendered with
antimicrobial properties by applying a coating of silver containing
antimicrobial compositions. Silver ion-exchange compounds, silver
zeolites and silver glasses are all known to be applied to fibers
through topical applications for the purpose of providing
antimicrobial properties to the fiber as described in U.S. Pat. No.
6,499,320, U.S. Pat. No. 6,584,668, U.S. Pat. No. 6,640,371 and
U.S. Pat. No. 6,641,829. Other inorganic antimicrobial agents may
be contained in a coating that is applied to a fiber as described
in U.S. Pat. No. 5,709,870, U.S. Pat. No. 6,296,863, U.S. Pat. No.
6,585,767 and U.S. Pat. No. 6,602,811. It is known in the art to
use binders to apply coating compositions to impart antimicrobial
properties to various substrates. U.S. Pat. No. 6,716,895 describes
the use of hydrophilic and hydrophobic polymers and a mixture of
oligodynamic metal salts as an antimicrobial composition, wherein
the water content in the coating composition is preferably less
than 50%. U.S. Pat. No. 5,709,870 describes the use of
carboxymethyl cellulose-silver complexes to provide an
antimicrobial coating to a fiber. The use of silver halides in an
antimicrobial coating, particularly for medical devices, is
described in U.S. Pat. No. 5,848,995.
[0009] US 2006/0068024 describes aqueous compositions for coating a
fabric or fiber with an antimicrobial comprising water, silver
halide particles and a hydrophilic polymer. It further describes a
composition comprising at least two separately packaged parts, the
first part being a composition comprising water, silver halide
particles and a hydrophilic polymer; and the second part being a
composition comprising an aqueous suspension of a hydrophobic
binder, or a composition comprising a crosslinker for the
hydrophilic polymer. The preferred hydrophilic polymer is gelatin.
Also described is a method of coating a fabric or fiber comprising
mixing the two separately packaged parts; and coating the mixture
on fabric or fiber. The described compositions impart durable
antimicrobial properties to yarn, fabrics or textiles. The silver
halide particles are applied to the target fiber or textile fabric
with the aid of a hydrophilic binder that imparts colloidal
stability to the particles prior to and during the application
process to the fiber or textile fabric. The composition may also be
aided with the use of a hydrophobic binder to impart improved
durability to extended washing cycles that would otherwise remove
the particles and the associated antimicrobial properties of the
fiber or textile fabric.
[0010] Various approaches to and compositions for treating
substrates such as fibers and textile fabrics with silver
antimicrobial compositions have been proposed. It is generally
desired, however, that the applied antimicrobial composition does
not negatively affect the other properties of the treated
substrate. In particular, the antimicrobial compositions are
typically desirably applied in an appropriate manner and at a
concentration so as not to significantly change the visual
appearance of the substrate. This desirable feature, however, makes
it difficult to easily verify whether an antimicrobial agent is
actually present in a treatment solution, and has actually been
effectively applied to a substrate. It accordingly would be
advantageous to provide a method for detecting the presence of
silver-containing antimicrobial agents on the surface of a
substrate, or presence of such agents in a treatment solution, to
verify whether a substrate has actually been treated with a silver
antimicrobial composition.
SUMMARY OF THE INVENTION
[0011] In accordance with one embodiment, the present invention is
directed towards a method for testing for presence of silver metal
or a silver salt on a surface of substrate, comprising a)
contacting the substrate with a dye solution, wherein the dye
solution comprises a dye selected to provide a detectable
differential color change in the dye solution contacted substrate
for a substrate having silver metal or silver salt on a surface
thereof relative to a substrate not having silver metal or silver
salt on a surface thereof, and b) detecting a presence or absence
of the differential color change in the dye solution contacted
substrate.
[0012] In accordance with a further embodiment, the invention is
also directed towards a method of coating a substrate with a
silver-containing composition to provide antimicrobial properties
comprising: providing a composition comprising a silver-containing
antimicrobial agent; providing a substrate; coating the substrate
with said composition; and verifying presence of silver-containing
antimicrobial agent deposited on a surface of the substrate by
contacting the substrate with a dye solution, wherein the dye
solution comprises a dye selected to provide a detectable
differential color change in the dye solution contacted substrate
for a substrate having silver-containing antimicrobial agent on a
surface thereof relative to a substrate not having
silver-containing antimicrobial agent on a surface thereof, and
detecting a presence or absence of the differential color change in
the dye solution contacted substrate.
[0013] In accordance with a further embodiment, the invention is
also directed towards a method for testing for presence of
silver-containing antimicrobial agent in a treatment solution,
comprising a) contacting a sample of the treatment solution with a
dye solution, wherein the dye solution comprises a dye selected to
provide a detectable differential color change in the dye solution
contacted treatment solution for a treatment solution having
silver-containing antimicrobial agent therein relative to a
treatment solution not having silver-containing antimicrobial agent
therein, and b) detecting a presence or absence of the differential
color change in the dye solution contacted treatment solution. In
such embodiment, the treatment solution may be subsequently used to
coat a substrate with the silver-containing antimicrobial
agent.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a graph showing the reflection optical density of
the dyed samples of Examples 2a-2d measured as a function of
wavelength.
[0015] FIG. 2 is a graph showing the Delta Reflection Densities in
Table 2 of Example 2 plotted as a function of padded silver
chloride level.
DETAILED DESCRIPTION OF THE INVENTION
[0016] The present invention in one embodiment provides a method
for testing for presence of silver metal or a silver salt deposited
on a surface of a substrate. In such method, the substrate to be
tested is contacted with a dye solution, wherein the dye solution
comprises a dye selected to provide a detectable differential color
change in the dye solution contacted substrate for a substrate
having silver metal or silver salt on a surface thereof relative to
a substrate not having silver metal or silver salt on a surface
thereof. In various particular embodiments, the dye solution may
comprise a dye selected to have adsorption affinity for a silver
salt, and the dye solution may test directly for the presence of a
silver salt, or test indirectly for the presence of silver metal by
converting a surface of the silver metal in situ to a silver salt.
Upon adsorption of the dye, a detectable differential color change
in the dye solution contacted substrate is obtained for a substrate
having silver metal or silver salt on a surface thereof relative to
a substrate not having silver metal or silver salt on a surface
thereof. By detecting a presence or absence of the differential
color change in the dye solution contacted substrate, the presence
or absence of silver metal or silver salt may be confirmed.
[0017] In a particular embodiment the invention is directed
specifically towards a test for the presence of silver halide
particles. As taught in US 2006/0068024 referenced above, e.g., the
disclosure of which is incorporated herein by reference in its
entirety, silver halide dispersions have been found to be effective
for treating substrates such as fibers and textile fabrics to
provide antimicrobial properties. Photographic sensitizing dyes are
a well known class of dyes known to have adsorption affinity for
silver halide particles, and may be conveniently employed as the
dye in the dye solution in such embodiment.
[0018] It is common in the art of spectral sensitization of silver
halide emulsions, e.g., to use cyanine dyes that transfer the
energy of adsorbed light to the conduction band of the silver
halide, thus making the silver halide sensitive to wavelengths
longer than its native sensitivity. Along with the ability to
transfer the energy of adsorbed light to the silver halide,
sensitizing dyes must also have the ability to effectively adsorb
to silver halide so as to enable such transfer of energy. It is
this known affinity for adsorption to silver halide that make such
known class of dyes appropriate for use in the present invention.
Photographic sensitizing dyes are well known in the art and are
disclosed, for example, in Research Disclosure, September 1996,
38957, Section V. Research Disclosure is published by Kenneth Mason
Publications, Ltd., Dudley House, 12 North St., Emsworth, Hampshire
PO10 7DQ, England. The dyes useful in the invention can be prepared
by synthetic techniques well known in the art. Such techniques are
further illustrated, for example, in "The Cyanine Dyes and Related
Compounds", Frances Hamer, Interscience Publishers, 1964 and "The
Theory of the Photographic Process", T. H. James, ed., 4th Edition,
Macmillan (1977).
[0019] The dye solutions used in the invention can employ dyes from
a variety of classes, including the polymethine dye class, which
includes the cyanines, merocyanines, complex cyanines and
merocyanines (i.e., tri-, tetra- and polynuclear cyanines and
merocyanines), styryls, merostyryls, streptocyanines, hemicyanines,
arylidenes, allopolar cyanines and enamine cyanines. Cyanine dyes
include, joined by a methine linkage, two basic heterocyclic
nuclei, such as those derived from quinolinium, pyridinium,
isoquinolinium, 3H-indolium, benzindolium, oxazolium, thiazolium,
selenazolinium, imidazolium, benzoxazolium, benzothiazolium,
benzoselenazolium, benzotellurazolium, benzimidazolium,
naphthoxazolium, naphthothiazolium, naphthoselenazolium,
naphtotellurazolium, thiazolinium, dihydronaphthothiazolium,
pyrylium and imidazopyrazinium quaternary salts. Merocyanine dyes
include, joined by a methine linkage, a basic heterocyclic nucleus
of the cyanine-dye type and an acidic nucleus such as can be
derived from barbituric acid, 2-thiobarbituric acid, rhodanine,
hydantoin, 2-thiohydantoin, 4-thiohydantoin, 2-pyrazolin-5-one,
2-isoxazolin-5-one, indan-1,3-dione, cyclohexan-1,3-dione,
1,3-dioxane-4,6-dione, pyrazolin-3,5-dione, pentan-2,4-dione,
alkylsulfonyl acetonitrile, benzoylacetonitrile, malononitrile,
malonamide, isoquinolin-4-one, chroman-2,4-dione, 5H-furan-2-one,
SH-3-pyrrolin-2-one, 1,1,3-tricyanopropene and
telluracyclohexanedione.
[0020] Among useful spectral sensitizing dyes known to have
adsorption affinity for silver halide are those found in U.K.
Patent 742,112, Brooker U.S. Pat. Nos. 1,846,300, '301, '302, '303,
'304, 2,078,233 and 2,089,729, Brooker et al U.S. Pat. Nos.
2,165,338, 2,213,238, 2,493,747, '748, 2,526,632, 2,739,964
(Reissue 24,292), U.S. Pat. No. 2,778,823, 2,917,516, 3,352,857,
3,411,916 and 3,431,111, Sprague U.S. Pat. No. 2,503,776, Nys et al
U.S. Pat. No. 3,282,933, Riester U.S. Pat. No. 3,660,102, Kampfer
et al U.S. Pat. No. 3,660,103, Taber et al U.S. Pat. Nos.
3,335,010, 3,352,680 and 3,384,486, Lincoln et al U.S. Pat. No.
3,397,981, Fumia et al U.S. Pat. Nos. 3,482,978 and 3,623,881,
Spence et al U.S. Pat. No. 3,718,470 and Mee U.S. Pat. No.
4,025,349, the disclosures of which are here incorporated by
reference. One or more dyes may be employed in combination.
[0021] Furthermore, in the spectral sensitization of silver halide
emulsions for color photographic applications, it is customary to
use J-aggregating cyanine dyes because of the narrower light
absorption of the aggregate and the improved color separation that
it provides (see The Theory of the Photographic Process, 4th
edition, T. H. James, editor, Macmillan Publishing Co., New York,
1977, for a discussion of aggregation). Use of J-aggregating
cyanine dyes may be particularly advantageous for providing a
signal for the presence of silver halide on a substrate in
accordance with the method of the present invention.
[0022] The following illustrate specific dyes that may be employed
in various embodiments of the present invention:
##STR00001##
[0023] Dye solutions employed in the present invention are
preferably aqueous based, but may also preferably comprise a minor
percentage of organic solvent such as methanol. In a particularly
preferred embodiment, dye solutions employed to test for the
presence of silver halide salts on a substrate may include soluble
halide salts, and in particular bromide or iodide salts, in an
amount effective to enhance the detectable differential color
change in the dye solution contacted substrate obtained for a
substrate having silver halide particles on a surface thereof
relative to a substrate not having silver halide particles on a
surface thereof, as the presence of such halide ions in solution
has been found to enhance the adsorption of sensitizing dyes on
silver halide surfaces, especially when the silver halide is
predominantly silver chloride. In an alternative embodiment, dye
solutions containing soluble halide salts may be employed in the
present invention to test for the presence of metallic silver on a
substrate, wherein the soluble halide salt serves the purpose of
facilitating conversion of the surface of the metallic silver to
silver halide in the presence of environmental oxygen (or other
added oxidizing agent) dissolved in the dye solution. In this
embodiment, soluble iodide is particularly preferred for inclusion
in the dye solution.
[0024] Dyes may be selected for use in the present invention such
that adsorption of dye to silver halide particles on a substrate
preferably results in a differential color change that is human
visually detectable. Accordingly when employing a colored
substrate, it may be preferable to select a dye from known colored
dyes based on the color of the substrate to provide a human
visually detectable differential color change. Even if not readily
human visually detectable, dyes may be selectively adsorbed such
that the presence or absence of silver on a substrate results in a
differential optical reflection density spectrum for the dye
solution contacted substrate.
[0025] The present invention further provides a method of coating a
substrate with a silver-containing composition to provide
antimicrobial properties comprising: providing a composition
comprising a silver-containing antimicrobial agent; providing a
substrate; coating the substrate with said composition; and
verifying presence of silver-containing antimicrobial agent
deposited on a surface of the substrate by contacting the substrate
with a dye solution, wherein the dye solution comprises a dye
selected to provide a detectable differential color change in the
dye solution contacted substrate for a substrate having
silver-containing antimicrobial agent on a surface thereof relative
to a substrate not having silver-containing antimicrobial agent on
a surface thereof, and detecting a presence or absence of the
differential color change in the dye solution contacted substrate.
The composition preferably comprises water, silver halide
particles, and a binder; and the dye solution preferably comprises
a dye having a greater adsorption affinity for silver halide
relative to that for the substrate or has a detectable different
color when adsorbed to silver halide relative to color when
adsorbed to the substrate.
[0026] The method of the invention may be performed on an actual
end product treated with silver-containing treatment solution to
instill antimicrobial properties, or alternatively, the present
invention may be employed on a test substrate previously treated
with a substrate treatment solution to verify presence or absence
of silver-containing antimicrobial agent in the substrate treatment
solution, prior to use of the treatment solution to actually treat
a desired end product. In such latter embodiment, it may be
desirable to select a test substrate that provides a human visually
detectable differential color change, especially where use of a dye
solution for detection of silver on the actual desired end product
may not provide a strong visual signal.
[0027] In a further embodiment, the invention provides a method for
testing for presence of silver-containing antimicrobial agent in a
treatment solution itself, such as a treatment solution intended
for processing a substrate to coat the substrate with
silver-containing antimicrobial agent. In such embodiment, a sample
of the treatment solution is contacted with a dye solution, wherein
the dye solution comprises a dye selected to provide a detectable
differential color change in the dye solution contacted treatment
solution for a treatment solution having silver-containing
antimicrobial agent therein relative to a treatment solution not
having silver-containing antimicrobial agent therein, and a
presence or absence of the differential color change in the dye
solution contacted treatment solution is detected to verify the
presence or absence of silver-containing antimicrobial agent. The
treatment solution may comprise, e.g., water, silver halide
particles, and a binder; and the dye solution may comprise a dye
having adsorption affinity for silver halide and which provides a
detectable different color when adsorbed to silver halide relative
to color when not adsorbed to silver halide. Similarly as when
testing for the presence of silver metal on a surface of substrate,
dye solutions containing soluble halide salts may be employed in
the present invention to test for the presence of metallic silver
in a treatment solution, wherein the soluble halide salt serves the
purpose of facilitating conversion of the surface of the metallic
silver to silver halide in the presence of environmental oxygen (or
other added oxidizing agent) dissolved in the dye solution.
Additionally, dye solutions containing soluble halide salts may be
employed in the present invention to test for the presence of
soluble silver in a treatment solution, wherein the soluble halide
and soluble silver react in situ to precipitate silver halide
particles to which the dye of the dye solution may adsorb.
[0028] As taught in US 2006/0068024, silver halide antimicrobial
compositions preferably may comprise at least 50% water by weight,
silver halide particles, and a hydrophilic polymer. The hydrophilic
polymer preferably is of a type and used in an amount wherein the
composition does not substantially gel or solidify at 25 degrees C.
In practical terms the composition, when sold as a concentrate,
should be able to flow at 25 degrees C. and be easily mixed with an
aqueous diluent or other addenda prior to use as an antimicrobial
coating for yarn or textile. The composition also encompasses a
more diluted form that is suitable for dip, pad, or other types of
coating. In one embodiment, e.g., it comprises at least 70% water
by weight. In its most diluted form the composition may be greater
than 95% water. The composition is preferably substantially free of
organic solvents. Preferably, no organic solvent is intentionally
added to the composition. The composition exhibits antimicrobial
activity upon drying.
[0029] The silver halide particles may be of any shape and halide
composition. The type of halide may include chloride, bromide,
iodide and mixtures of them. The silver halide particles may be,
for example, silver bromide, silver iodobromide, bromoiodide,
silver iodide or silver chloride. In one embodiment the silver
halide particles are predominantly silver chloride. The
predominantly silver chloride particles may be, for example, silver
chloride, silver bromochloride, silver iodochloride, silver
bromoiodochloride and silver iodobromochloride particles. By
predominantly silver chloride, it is meant that the particles are
greater than about 50 mole percent silver chloride. Preferably,
they are greater than about 90 mole percent silver chloride; and
optimally greater than about 95 mole percent silver chloride. The
silver halide particles may either be homogeneous in composition or
the core region may have a different composition than the shell
region of the particles. The shape of the silver halide particles
may be cubic, octahedral, tabular or irregular. More silver halide
properties may be found in "The Theory of the Photographic
Process", T. H. James, ed., 4th Edition, Macmillan (1977). In one
embodiment the silver halide particles have a mean equivalent
circular diameter of less than 1 micron, and preferably less 0.5
microns.
[0030] The solubility of silver halide, hence the free silver ion
concentration, is determined by the solubility product (Ksp),
particle size, structure and shape of the particle. While not being
held to the theory, it is believed that the free silver ion
concentration plays a role in antimicrobial efficacy. By
controlling the above variables one can control silver ion release
rate and antimicrobial activity.
[0031] The silver halide particles and associated coating
composition preferably may be applied to a substrate such as a
fiber or fabric in an amount sufficient to provide antimicrobial
properties to the treated substrate for a minimum of at least 10
washes, more preferably 20 washes and most preferably after 30
washes in accordance with the standard domestic washing and drying
procedure for textile testing ISO 6330:2003 published by the
International Organization for Standardization, Geneva,
Switzerland. The amount of silver halide particles applied to the
target substrate is determined by the desired durability or length
of time of antimicrobial properties. The amount of silver halide
particles present in the composition will depend on whether the
composition is one being sold in a concentrated form suitable for
dilution prior to coating or whether the composition has already
been diluted for coating. Typical levels of silver salt particles
(by weight percent) in the formulation are preferably from about
0.000001% to about 10%, more preferably from about 0.0001% to about
1% and most preferably from about 0.001% to 0.5%. In a concentrated
format the composition preferably comprises silver halide particles
in an amount of 0.001 to 10%, more preferably 0.001 to 1%, and most
preferably 0.001 to 0.5%. In a diluted format the composition
preferably comprises silver halide particles in an amount from
about 0.000001% to about 0.01%, more preferably from about 0.00001%
to about 0.01% and most preferably from about 0.0001% to 0.01%. It
is a desirable feature to provide efficient antimicrobial
properties to the target substrate at a minimum silver halide level
to minimize the cost associated with the antimicrobial
treatment.
[0032] The preferred hydrophilic polymers employed in silver halide
particle antimicrobial compositions coated in particular
embodiments of the present invention are soluble in water at
concentrations greater than about at least 2%, preferably greater
than 5%, and more preferably greater than 10%. Therefore, suitable
hydrophilic polymers do not require an organic solvent to remain
fluid at 25 degrees C. Suitable useful hydrophilic polymers
include, for example, gelatin, polyacrylic acid, polyacrylamide,
polyvinyl alcohol, polyvinylpyrrolidones, cellulose etc. The
polymers peptize or stabilize silver halide particles to help
maintain colloidal stability of the solution. A preferred
hydrophilic polymer is gelatin.
[0033] Gelatin is an amphoteric polyelectrolyte that has excellent
affinity to a number of substrates. Gelatin may be processed by any
of the well-known techniques in the art including;
alkali-treatment, acid-treatment, acetylated gelatin, phthalated
gelatin or enzyme digestion. The gelatin may have a wide range of
molecular weights and may include low molecular weight gelatins if
it is desirable to raise the concentration of the gelatin in the
antimicrobial composition without solidifying the composition. The
gelatin is preferably added in an amount sufficient to peptize the
surface of the silver halide and some excess of gelatin will always
be present in the water phase. The gelatin level may be chosen such
that the composition does not substantially solidify or gel. In one
embodiment the weight percentage of gelatin is less than 3%,
preferably less than 2%, and more preferably less than 1%. The
gelatin may also be cross-linked in order to improve the durability
of the coating composition containing the antimicrobial silver
halide particles.
[0034] Silver halide particles may be formed by reacting silver
nitrate with halide in aqueous solution. In the process of silver
halide precipitation one can add hydrophilic polymers to peptize
the surface of the silver halide particles thereby imparting
colloidal stability to the particles, see for example, Research
Disclosure September 1997, Number 40122 published by Kenneth Mason
Publications, Ltd., Dudley Annex, 12a North Street, Emsworth,
Hampshire PO10 7DQ, ENGLAND, the contents of which are incorporated
herein by reference.
[0035] In addition to hydrophilic binder, a hydrophobic binder
resin is preferably used to improve the adhesion and durability of
the silver salt particles once applied to the substrate surface.
Such hydrophobic binders are well known in the art and are
typically provided as aqueous suspensions of polymer
microparticles. Materials suitable for use as hydrophobic binders
include acrylic, styrene-butadiene, polyurethane, polyester,
polyvinyl acetate, polyvinyl acetal, vinyl chloride and vinylidine
chloride polymers, including copolymers thereof. Acrylic polymers
and polyurethane are preferred.
[0036] The hydrophobic binders should have film-forming properties
that include a range of glass transition temperatures from about
-30 C to about 90 C. The hydrophobic binder particles may have a
wide range of particle sizes from about 10 nm to about 10,000 nm
and can be polydisperse in distribution. The hydrophobic binders
may also be thermally or chemically crosslinkable in order to
modify the desired durability properties of the antimicrobial
composition treated substrate (e.g., fiber or fabric textile). The
hydrophobic binders may be nonionic or anionic in nature. Useful
ranges of the hydrophobic binders are generally less than about 10%
of the composition. It is understood that the choice of the
hydrophobic binder may be related to specific end use requirements
of the substrate, including, e.g., wash resistance, abrasion
(crock), tear resistance, light resistance, coloration, hand and
the like for fiber or fabric textile substrates. As described in
more detail below the hydrophobic binder is generally preferably
kept separate from the hydrophilic polymer/silver halide particle
composition until a short time prior to coating.
[0037] As noted above, the antimicrobial composition may also
comprise a crosslinker for the gelatin. The crosslinker is also
generally kept separate from the hydrophilic polymer/silver halide
particle composition until a short time prior to coating. Examples
of compounds useful in crosslinking the gelatin include, but are
not limited to, Alum, formaldehyde and free dialdehydes such as
glutaraldehyde, bis(iminomethyl)ether salts, strazines and
diazines, such as dihydroxychlorotriazine, epoxides, aziridines,
and the like.
[0038] Treatment solutions comprising a silver-containing
antimicrobial agent, and in particular antimicrobial compositions
comprising silver-containing antimicrobial agent, hydrophilic
binder and optionally, hydrophobic binder or gelatin cross-linker,
can be applied to a target substrate, such as a fiber or textile
fabric, in any of the well know methods in art including, pad
coating, knife coating, screen coating, spraying, foaming and
kiss-coating. In a specific embodiment, components of the
antimicrobial composition are preferably delivered as a separately
packaged two-part system involving colloidal silver halide
particles and hydrophilic binder as one part and a second part
comprising an aqueous suspension of a hydrophobic binder, or
gelatin cross-linker and, optionally, a second hydrophilic binder
that may be the same or different as the hydrophilic binder from
the first part. The first part, comprising colloidal silver halide
particles and hydrophilic binder, is excellent in shelf-life
without compromising colloidal stability. The two parts may be
combined prior to a padding or coating operation and exhibit
colloidal stability for the useful shelf-life of the composition,
typically on the order of several days.
[0039] There may also be present further optional components, for
example, thickeners or wetting agents to aid in the application of
the antimicrobial composition to the target substrate. Examples of
wetting materials include surface active agents commonly used in
the art such as ethyleneoxide-propyleneoxide block copolymers,
polyoxyethylene alkyl phenols, polyoxyethylene alkyl ethers, and
the like. Compounds useful as thickeners include, for example,
particulates such as silica gels and smectite clays,
polysaccharides such as xanthan gum, polymeric materials such as
acrylic-acrylicacid copolymers, hydrophobically modified
ethoxylated urethanes, hydrophobically modified nonionic polyols,
hydroxypropyl methylcellulose and the like.
[0040] Also of use in the compositions is an agent to prevent
latent image formation. Some silver salts are light sensitive and
discolor upon irradiation of light. However, the degree of light
sensitivity may be minimized by several techniques known to those
who are skilled in the art. For example, storage of the silver
halide particles in a low pH environment will minimize
discoloration. In general, pH below 7.0 is desired and more
specifically, pH below 4.5 is preferred. Another technique to
inhibit discoloration involves adding compounds of elements, such
as, iron, iridium, rhuthinium, palladium, osmium, gallium, cobalt,
rhodium, and the like, to the silver halide particles. These
compounds are known in the photographic art to change the
propensity of latent image formation; and thus the discoloration of
the silver salt. Additional emulsion dopants are described in
Research Disclosure, February 1995, Volume 370, Item 37038, Section
XV.B., published by Kenneth Mason Publications, Ltd., Dudley Annex,
12a North Street, Elmsworth, Hampshire PO11 7DQ, England. In any
event, discoloration due to latent image formation, while
cosmetically undesirable for the antimicrobial composition itself,
will typically not have a substantially negative impact on the
treated substrate, as the silver halide particles are applied at a
relatively low concentration.
[0041] While the invention has been primarily described with
respect to detection of silver halide salts, selection of
appropriate dyes having the desired relative adsorption affinities
and/or color change properties to achieve detectable differential
color change properties for a variety of silver based compositions
relative to a particular substrate will be within the skill of the
artisan. As described above, detection of silver metal in various
embodiments of the invention may be accomplished by employing a dye
having adsorption affinity for a silver salt, wherein the dye
solution also in situ converts surface of silver metal to a silver
salt. Various oxidizing agents, including environmental oxygen, may
be used to convert silver metal to silver ions, and dyes solutions
may include soluble halide salts, and in particular bromide or
iodide salts, in an amount effective to form silver halide surfaces
with adsorption affinity for a selected dye, which may enhance the
detectable differential color change in the dye solution contacted
substrate or treatment solution.
[0042] The present invention is not limited to treatment of, and
detection of silver-containing antimicrobial agent on, any
particular substrate. Any fiber or textile fabric or yarn may be
employed, e.g., including, exhaustively any natural or manufactured
fibers, and blends thereof. Examples of natural fibers include,
cotton (cellulosic), wool, or other natural hair fibers, for
example, mohair and angora. Examples of manufactured fibers include
synthetics, such as, polyester, polyolefins such as polyethylene
and polypropylene, nylon, acrylic, polyamide, polyether block amide
including PEBAX, polycarbonate resins, polyvinylpyrolidinone,
polyethylene oxide, and the like, as well as their interpolymers
and blends, unsaturated polyesters, alkyds, phenolic polymers,
amino plastics, epoxy resins, polyurethanes, polysulfides,
polystyrene, or, regenerated materials such as cellulosics. As
demonstrated in the examples below, e.g., the presence of silver
halide particles deposited on the surface of a variety of
substrates may be detected with dye solutions comprising selected
dyes having a greater adsorption affinity for silver halide
relative to that for the substrates, wherein a detectable different
color is obtained when adsorbed to silver halide relative to color
when adsorbed to the substrate. The target substrate may further
include any number of chemistries or applications prior to, during
and/or after the application of the antimicrobial composition
including, for example, antistatic control agents, flame
retardants, soil resistant agents, wrinkle resistant agents, shrink
resistant agents, dyes and colorants, brightening agents, UV
stabilizers, lubricants, antimigrants, and the like.
[0043] The following examples are intended to demonstrate, but not
to limit, the invention.
EXAMPLE 1
[0044] This example shows that DYE-1 can discriminate between
sections of a fabric that have been treated with an antimicrobial
treatment containing AgCl and those that have not.
[0045] Padding Bath A was prepared by mixing (1) a silver
chloride/gelatin emulsion in water (silver index .about.1.036
kg/mole silver, gelatin level .about.19.2 g/mole) like that
described in Example 1 in US 2006/0068024, (2) an acrylic binder
dispersion (RHOPLEX.RTM. TS-934HS, Rohm and Haas Co., Philadelphia,
Pa., USA) and (3) water in the following percentages:
TABLE-US-00001 Padding Bath A Component Wt % AgCl 0.0076 gelatin
0.0010 acrylic binder 0.2500 water 99.740
[0046] Two sections of a 10 inch long.times.5 inch wide sample of
white Spun Polyester Fabric (Style #777, Testfabrics Inc., West
Pittston, Pa., USA) were masked by applying plastic-coated tape
across the full width of both sides of the fabric for a distance of
1 inch beginning at a line approximately 2 inches from one end of
the sample, and again for a distance of two inches beginning at a
line approximately six inches from the same end. In this way the
sample was made to contain two bands, one 1 inch wide and a second
2 inches wide that were inaccessible to the components of any
liquid bath in which the fabric was immersed.
[0047] This masked fabric sample was immersed in Padding Bath A for
approximately 5 seconds, removed from the bath and passed through a
pressurized nip/roller system in which the pressure was set to
achieve a wet pickup [((weight of fabric after bath)-(weight of dry
fabric))/(weight of dry fabric)] of approximately 80%. The sample
was then heated to 315 F. for approximately 3 minutes to crosslink
the acrylic binder. After this heating step, the tape was removed.
Once the tape was removed, there was no obvious visual difference
between the masked and unmasked areas of the fabric.
[0048] Dyeing Solution 1A was prepared by mixing (1) DYE-1, (2)
methyl alcohol, (3) potassium iodide and (4) water in the following
amounts:
TABLE-US-00002 Dyeing Solution 1A Component amount DYE-1 0.00996
grams potassium iodide 0.06640 grams methyl alcohol 100.0 mls water
300.0 mls
[0049] The fabric sample prepared above was immersed in Dyeing
Solution 1A for 1 minute at room temperature (.about.23.5 C.). The
fabric was then removed from the dyeing solution, rinsed in 1 liter
of water at room temperature for 1 minute and then dried. Visual
inspection of the dried strip showed that the sections of the
fabric that had not been covered by tape during the padding
operation had adsorbed DYE-1 and had changed color from white to
magenta. The two bands that had been masked during the padding
operation did not adsorb the dye and remained white.
EXAMPLE 2
[0050] This example shows that the invention process can quantify
the amount of a silver-based antimicrobial applied to a fabric.
[0051] Padding Baths B thru E were prepared by mixing the same
components used to prepare Padding Bath A in Example 1 except that
the percentages shown in Table 1 were used. If the silver chloride
level in Bath C is taken as 1.times., then the silver chloride in
Baths B, D, and E are 0.times., 2.times., 3.times.,
respectively.
TABLE-US-00003 TABLE 1 Padding Bath Component B C D E Silver
chloride 0.00000 0.00927 0.01854 0.02781 Gelatin 0.00127 0.00127
0.00127 0.00127 Acrylic binder 0.31250 0.31250 0.31250 0.31250
Water 99.69 99.68 99.67 99.66
[0052] Separate samples of undyed (white) Spun Polyester Fabric
(Testfabrics Inc., style #777) were immersed in Padding Baths B
thru E for approximately 5 seconds (designated Examples 2a, 2b, 2c
2d, respectively), removed from the bath and passed through a
pressurized nip/roller system in which the pressure was set to
achieve a wet pickup of approximately 80%. The samples were then
heated to approximately 350 F. for 20 minutes to crosslink the
acrylic binder.
[0053] Dyeing Solution 1B was prepared by mixing (1) DYE-1, (2)
methyl alcohol, (3) sodium iodide and (4) water in the following
amounts:
TABLE-US-00004 Dyeing Solution 1B Component amount DYE-1 0.00499
grams sodium iodide 0.00292 grams methyl alcohol 10.0 mls water to
a total volume of 100.0 mls
[0054] The padded fabric samples Examples 2a thru 2d were dyed
using Dyeing Solution 1B according to the following protocol: (1)
presoak the samples in room temperature water (.about.23 C.) for 1
minute; (2) immerse in Dyeing Solution 1B at 25 C. for 5 minutes;
(3) wash in running water for 3 minutes at room temperature; (4)
dry. The reflection optical density of the dyed samples was
measured as a function of wavelength using a Spectrolino
spectrophotometer (GretagMacbeth Corp., Regensdorf, Switzerland),
operating in a reflection measurement mode. These reflection
optical density spectra are shown in FIG. 1. Curve a in FIG. 1
shows the reflectance spectrum for dyed sample Example 2a, which
contained no padded silver chloride. The spectrum of dyed sample
Example 2a is characterized by a single, broad band centered at
wavelength W2 (.about.540 nm). Curves b, c, and d in FIG. 1 are the
reflectance spectra for dyed samples of Examples 2b, 2c, and 2d,
respectively. They show the growth of a new band--not present in
the dyed sample of Example 2a--at wavelength W1 (580-590 nm), that
increases in intensity as the level of silver chloride increases.
Another band whose intensity also increases with silver chloride
level appears in the dyed samples of Examples 2b, 2c, and 2d at
wavelength W3 (.about.410 nm). Delta Reflection Densities
corresponding to the three silver chloride levels used in the dyed
samples of Examples 2b, 2c and 2d are shown in Table 2, wherein the
Delta Reflection Density represents the increase in refection
optical density relative to the reflection optical density of dyed
Sample 2a (no padded silver chloride). The Delta Reflection
Densities in Table 2 are plotted as a function of padded silver
chloride level in FIG. 2, which demonstrates an excellent
correlation between the increase in reflection optical density of
the dyed samples at wavelengths W1 and W3 and the silver chloride
level padded on the dyed fabrics.
TABLE-US-00005 TABLE 2 Delta Reflection Density (Reflection density
minus reflection Silver Chloride density of Sample 2a) Level in
Padding W3 W1 Example Bath 410 nm 590 nm 2a 0x -- -- 2b 1x 0.0618
0.0789 2c 2x 0.0989 0.1458 2d 3x 0.1255 0.2147
EXAMPLE 3
[0055] This example shows that a number of dyes can be used in the
process of the invention to detect a silver-based antimicrobial
applied to different types of fabric.
[0056] Three fabrics were obtained from Testfabrics Inc.: Spun
Polyester (style #777); Cotton Sheeting (style #493); and
Polyester/Cotton Blend, 65/35 (style #7436). Samples of each of the
fabric types were padded and cured using Padding Baths E and B of
Example 2, resulting in sample pairs with and without a silver
chloride antimicrobial coating, respectively. The original fabrics
were undyed, and showed no color as received or after the padding
and curing process.
[0057] Dyeing Solutions 2A thru 5 were prepared exactly as Dyeing
Solution 1B of Example 2 except that DYE-1 was replaced as shown in
Table 3.
TABLE-US-00006 TABLE 3 Dyeing Solution Dye Grams 2A DYE-2 0.00774 3
DYE-3 0.00774 4 DYE-4 0.00632 5 DYE-5 0.00727
[0058] The six padded fabric samples were dyed using each of the
five Dyeing Solutions 1B, 2A, 3, 4, 5 according to the following
protocol: (1) presoak the samples in room temperature water
(.about.23 C.) for 1 minute; (2) immerse in a Dyeing Solution at 60
C. for 1 minute; (3) wash in running water for 3 minutes at room
temperature; (4) dry. Reflection optical density spectra were
measured for each of the thirty dyed samples produced. The dyed
samples are listed in Table 4 along with the wavelengths W2 and W1
(see FIG. 1) for each of the dyes on the fabrics, as well as the
reflection optical densities at each of those wavelengths. The
color of each of the samples determined from visual inspection of
the dyed samples is also given.
TABLE-US-00007 TABLE 4 Reflection density AgCl Reflection
Reflection ratio Sample on W2 density W1 density (at W1/at visual
color Sample Fabric fabric Dye (nm) at W2 (nm) at W1 W2) after
dyeing 4-A-1 Polyester Yes DYE-1 540 0.1934 580 0.2650 1.3702
Magenta 4-A-2 '' No '' '' 0.1121 '' 0.0815 0.7270 no color 4-B-1
Cotton Yes '' '' 0.5922 '' 0.1853 0.3129 magenta/salmon 4-B-2 '' No
'' '' 0.5348 '' 0.0969 0.1812 magenta/salmon 4-C-1 poly/cotton Yes
'' '' 0.4659 '' 0.1579 0.3389 Magenta 4-C-2 '' No '' '' 0.4672 ''
0.0878 0.1879 Magenta 4-D-1 polyester Yes DYE-2 510 0.2363 540
0.2613 1.1058 Magenta 4-D-2 '' No '' '' 0.1054 '' 0.0874 0.8292 no
color 4-E-1 cotton Yes '' '' 0.2287 '' 0.1302 0.5693 salmon/magenta
4-E-2 '' No '' '' 0.1971 '' 0.0160 0.0812 lime-yellow 4-F-1
poly/cotton Yes '' '' 0.1479 '' 0.1037 0.7011 Magenta 4-F-2 '' No
'' '' 0.1354 '' 0.0411 0.3035 no color 4-G-1 polyester Yes DYE-3
520 0.1544 550 0.1818 1.1775 Magenta 4-G2 '' No '' '' 0.0958 ''
0.0748 0.7808 no color 4-H-1 cotton Yes '' '' 0.1270 '' 0.0989
0.7787 Salmon 4-H-2 '' No '' '' 0.1225 '' 0.0282 0.2302 Lime 4-I-1
poly/cotton Yes '' '' 0.1048 '' 0.0973 0.9284 Magenta 4-I-2 '' No
'' '' 0.1016 '' 0.0493 0.4852 no color 4-J-1 polyester Yes DYE-4
440 0.2100 470 0.1651 0.7862 lime-yellow 4-J-2 '' No '' '' 0.1619
'' 0.0724 0.4472 lime-yellow 4-K-1 cotton Yes '' '' 0.3767 ''
0.1064 0.2825 lime-yellow 4-K-2 '' No '' '' 0.3526 '' 0.0260 0.0737
lime-yellow 4-L-1 poly/cotton Yes '' '' 0.2519 '' 0.1220 0.4843
lime-yellow 4-L-2 '' No '' '' 0.2216 '' 0.0133 0.0600 lime-yellow
4-M-1 polyester Yes DYE-5 440 0.2669 470 0.2905 1.0884 Yellow 4-M-2
'' No '' '' 0.1447 '' 0.0848 0.5860 no color 4-N-1 cotton Yes '' ''
0.4378 '' 0.1826 0.4171 yellow-green 4-N-2 '' No '' '' 0.4197 ''
0.0456 0.1086 yellow-green 4-O-1 poly/cotton Yes '' '' 0.2677 ''
0.1760 0.6575 yellow-green 4-O-2 '' No '' '' 0.2144 '' 0.0168
0.0784 yellow-green
[0059] The data in Table 4 show for each of the dyes tested the
presence of silver chloride on each of the three fabrics correlates
with the appearance of a new band at higher wavelength (W1) in the
reflectance spectrum such that for each sample pair (with and
without padded silver chloride) the ratio of the reflection density
at W1 to that at W2 is significantly higher for the sample
containing padded silver chloride. For all of the dyes except
DYE-4, the presence (or absence) of the silver chloride coating on
polyester can be directly assessed visually (color versus no color)
without having to measure the reflection spectrum, while for DYE-2
and DYE-3, there is sufficient color change for all three fabrics
when silver chloride is present to allow a direct, visual
verification that silver chloride had been applied to the
fabrics.
EXAMPLE 4
[0060] This example shows the impact of the presence of specific
soluble halide ions, particularly iodide ion, in the dyeing
solutions used to detect a padded silver chloride antimicrobial
using the process of the invention.
[0061] Dyeing Solutions 1C thru 1E were prepared as described for
Dyeing Solution 1B of Example 2 and Dyeing Solutions 2B thru 2D as
Dyeing Solution 2A of Example 3, except that the sodium iodide was
either omitted or replaced by an equal molar concentration of the
sodium halide shown in Table 5.
TABLE-US-00008 TABLE 5 Dyeing Solution Dye Sodium Halide 1C DYE-1
none 1D DYE-1 chloride 1E DYE-1 bromide 2B DYE-2 none 2C DYE-2
chloride 2D DYE-2 bromide
[0062] The polyester fabric (Spun Polyester style #777) samples
prepared with and without padded silver chloride in Example 3 were
dyed using Dyeing Solutions 1B thru 1E and 2A thru 2D according to
the protocol described in Example 3 and the reflection optical
density spectra of the dyed samples were recorded. The reflection
densities for each sample at wavelengths W1 and W2 (see FIG. 1) are
listed in Table 6 along with the ratios of the reflection density
at W1 to that at W2, along with visual color observations made on
the dyed samples.
TABLE-US-00009 TABLE 6 reflection density AgCl Dyeing reflection
reflection ratio on Dyeing Solution W2 density W1 density (at W1/at
sample color Sample fabric Dye Solution halide (nm) at W2 (nm) at
W1 W2) after dyeing 6-A-1 Yes DYE-1 1C none 540 0.1346 580 0.1023
0.7600 very slightly pink 6-A-2 No '' '' '' '' 0.1206 '' 0.0832
0.6899 very slightly pink 6-B-1 Yes '' 1D chloride '' 0.1381 ''
0.1047 0.7581 darker pink 6-B-2 No '' '' '' '' 0.1068 '' 0.0750
0.7022 very slightly pink 6-C-1 Yes '' 1E bromide '' 0.1522 ''
0.1472 0.9671 still darker pink 6-C-2 No '' '' '' '' 0.1184 ''
0.0812 0.6858 very slightly pink 6-D-1 Yes '' 1B iodide '' 0.2089
'' 0.2170 1.0388 full magenta 6-D-2 No '' '' '' '' 0.1115 '' 0.0774
0.6942 very slightly pink 6-E-1 Yes DYE-2 2B none 510 0.1109 540
0.0763 0.6880 no color 6-E-2 No '' '' '' '' 0.1062 '' 0.0795 0.7486
no color 6-F-1 Yes '' 2C chloride '' 0.0996 '' 0.0737 0.7400 no
color 6-F-2 No '' '' '' '' 0.1109 '' 0.0839 0.7565 no color 6-G-1
Yes '' 2D bromide '' 0.1243 '' 0.1082 0.8705 very slight orange
6-G-2 No '' '' '' '' 0.0958 '' 0.0724 0.7557 no color 6-H-1 Yes ''
2A iodide '' 0.1941 '' 0.2200 1.1334 full magenta 6-H-2 No '' '' ''
'' 0.1085 '' 0.0800 0.7373 no color
[0063] For DYE-1, the data in Table 6 show that the higher
wavelength band at W1 appears in the dyed samples containing padded
silver chloride even when halide ion is absent from the dyeing
solution. This is evidenced by the observation that the ratio of
the reflection density at W1 to that at W2 increases when silver
chloride is present on the coated fabric. While the increase is
relatively modest in the absence of halide in the dye solution, as
well as when chloride is added to the dye solution, the band begins
to appear much more prominently when bromide is present in the
dyeing solution, and increases dramatically in intensity when
iodide is present in the dyeing solution. For DYE-2, the effects of
bromide ion and iodide ion are even more dramatic as no significant
increase in the reflection density ratio (W1/W2) is seen until
either bromide or iodide is present in the dyeing solution. These
observations are also reflected in the visual appearance of the
dyed samples. For DYE-2, e.g., only when iodide was used in the
dyeing solutions did the dyed samples show the full magenta color
associated with the band at W1.
[0064] The invention has been described in detail with particular
reference to certain preferred embodiments thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
* * * * *